Plastic bags are commonly used in supermarkets, department stores and similar applications. These bags have advantages in that they are relatively inexpensive to produce, provide substantial carrying capacity and may include easily used handles. In order to make these bags easier to handle and easier to fill, they are usually used in combination with a dispensing rack or hook. Dispensing racks typically include a pair of horizontally oriented arms from which the bags are suspended by means of holes in upper portions of the bags. If the bags can be made to open as they are pulled from the dispensing rack or hook, they become substantially easier to use. Various techniques have been developed for causing plastic bags to open as they are removed from dispensing racks or hooks.
U.S. Pat. No. 4,811,417, issued to Prince et al. is directed to a handled bag with supporting slits in the handle. The bag-pack is mounted on a support rack that has a base and a pair of supporting arms, as well as mounting fingers for holding a tab portion. The plurality of bags comprising the bag-pack are joined together near the top of the handles by means of welds. The welds are formed using a hot pin.
U.S. Pat. No. 4,676,378 issued to Baxley et al., discloses a bag pack comprising a stack of thermoplastic shopping bags that are bound together and mounted on a rack in such a manner that as one is removed from the rack, the next is opened and remains on the rack to receive material therein. The rack that is used in this invention for the bag pack comprises a flat base with a pair of laterally spaced support arms to accommodate fully expanded bags with handles engaged with the support arms. A transverse member extends between the support arms to support a tab receiving hook element for engagement through the tab apertures. When the bag pack is produced, and either prior to or simultaneously with the forming of a cut line through the stacked bag handles, the flaps are bonded together throughout the full stack. This is done by use of a heated pin or rod extended centrally through the flaps to directly heat seal the flaps together.
U.S. Pat. No. 5,363,965, issued to Nguyen utilizes a self-opening thermoplastic bag system. The bags are supported on two horizontal arms that engage holes in the bag handles. The individual bags of the invention are held together in a bag pack via a heated or cold punch formed near the tab. The punches seen in this invention permeate the walls of the bags such that the rear wall of the next bag remains with the pack and is supported by the tab holding the opened bag in place on the rack as the lead bag is removed from the rack.
U.S. Pat. No. 5,207,328, issued to Bose et al is directed to a thermoplastic bag and bag pack. The bag is made of a thermoplastic material such as high molecular weight, high density polyethylene. Each of the handles of the bags comprise multiple layers of material which results from the configuration utilizing folded pleats, thus there are four layers of material for each of the handles. Each of the handles has an aperture extending through the layers of material in the form of an irregular shaped slit. When the slits are cut, the resulting slits in the material are connected at connection zones. This flexible connection permits loose interengagement of the layers of the inner slit material with some of the other layers of both the inner and outer slit materials. Thus, the need for cold welding or hot welding is eliminated and the alignment of the bags depends solely on the interengagement of the slit materials.
U.S. Pat. No. 5,469,970 issued to Li discloses easy open stackable handle bags. The system comprises a bag pack for use with a bag rack made up of a plurality of aligned individual handle bags. The bags each have an area of adhesive between each bag that allows for the front wall of the successive bag to be pulled from one side as the previous bag is pulled from the bag rack.
U.S. Pat. No. 5,865,313 issued to Huang et al. is directed to a plastic bag pack system with novel handle features. The central pad portions are preferably heat welded together, thus forming a stack of aligned central tab portions. The individual bags of the bag pack are treated on the outside surface by corona surface treatment that prepares the surfaces for receiving printing inks. When adjacent layers of corona surface treated plastic material are cut with a blade, they tend to frangibly bond together. This bonding gives rise to a self-opening feature. Both low density polyethylene and high density polyethylene may be used as the plastic material to form the bags described in this invention.
U.S. Pat. No. 6,079,877 issued to Chew discloses a plastic bag with triangular cut tabs. The outer walls of adjacent bags have been corona-treated and this treatment along with appropriately disposed pressure points enable the bags of the pack to be self-opening.
While other variations exist, the above-described designs for self-opening bag stacks are typical of those encountered in the prior art. It is an objective of the present invention to provide for a polyethylene bag stack that is suitable for use with standardized dispensing racks and includes a self-opening feature. It is a further objective to provide this capability in a bag stack that includes bags that are durable, break-resistant and easily produced. It is a still further objective of the invention to provide the above-described bag packs without the need for localized compressed areas in the bag stack.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.